Environment-dependent galactic dynamics: an effective phenomenological model for rotation curves using SPARC data (v2.0)

This repository presents a phenomenological effective model for galactic rotation curves that reproduces a significant fraction of SPARC observations without introducing exotic dark matter particles or modifying gravity. The model describes an environmental effective response associated with visible matter distributions, implemented through a minimal scalar-field formalism with fixed global parameters applied uniformly across the dataset. Numerical results show systematic improvements over purely baryonic models for approximately two-thirds of the SPARC galaxies, achieving a level of agreement qualitatively comparable to standard approaches such as ΛCDM and MOND, while relying on a distinct physical mechanism. This work is intended as a reproducible toy model and does not propose a fundamental theory. Its purpose is to explore whether part of the observed galactic dynamics can emerge from effective environmental responses without introducing new fundamental entities.